// -*- mode: java; c-basic-offset: 2; -*-
// Copyright 2009-2011 Google, All Rights reserved
// Copyright 2011-2012 MIT, All rights reserved
// Released under the Apache License, Version 2.0
// http://www.apache.org/licenses/LICENSE-2.0

package com.google.appinventor.components.runtime.collect;

import java.util.Collections;
import java.util.EnumSet;
import java.util.HashSet;
import java.util.SortedSet;
import java.util.TreeSet;

/**
 * Provides static methods for creating mutable {@code Set} instances easily and
 * other static methods for working with Sets.
 *
 * Note: This was copied from the com.google.android.collect.Lists class
 *
 * @author markf@google.com (Mark Friedman)
 */
public class Sets {

  /**
   * Creates an empty {@code HashSet} instance.
   *
   * <p><b>Note:</b> if {@code E} is an {@link Enum} type, use {@link
   * EnumSet#noneOf} instead.
   *
   * <p><b>Note:</b> if you only need an <i>immutable</i> empty Set,
   * use {@link Collections#emptySet} instead.
   *
   * @return a newly-created, initially-empty {@code HashSet}
   */
  public static <K> HashSet<K> newHashSet() {
    return new HashSet<K>();
  }

  /**
   * Creates a {@code HashSet} instance containing the given elements.
   *
   * <p><b>Note:</b> due to a bug in javac 1.5.0_06, we cannot support the
   * following:
   *
   * <p>{@code Set<Base> set = Sets.newHashSet(sub1, sub2);}
   *
   * <p>where {@code sub1} and {@code sub2} are references to subtypes of {@code
   * Base}, not of {@code Base} itself. To get around this, you must use:
   *
   * <p>{@code Set<Base> set = Sets.<Base>newHashSet(sub1, sub2);}
   *
   * @param elements the elements that the set should contain
   * @return a newly-created {@code HashSet} containing those elements (minus
   *     duplicates)
   */
  public static <E> HashSet<E> newHashSet(E... elements) {
    int capacity = elements.length * 4 / 3 + 1;
    HashSet<E> set = new HashSet<E>(capacity);
    Collections.addAll(set, elements);
    return set;
  }

  /**
   * Creates a {@code SortedSet} instance containing the given elements.
   *
   * @param elements the elements that the set should contain
   * @return a newly-created {@code SortedSet} containing those elements (minus
   *     duplicates)
   */
  public static <E> SortedSet<E> newSortedSet(E... elements) {
    SortedSet<E> set = new TreeSet<E>();
    Collections.addAll(set, elements);
    return set;
  }

}
